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Proceedings of IMPROVE Final Workshop

Design of Improved and Competitive Ships

using an Integrated Decision Support System

for Ship Production and Operation

Conference papers, Vol. I

Edited by

Vedran [email protected]

Faculty of Mechanical Engineering and Naval Architecture

University of Zagreb, Croatia

Jerolim [email protected]


University of Zagreb, Croatia

Project co-ordinator:

Philippe [email protected]

ANASTUniversity of Liege, Belgium

September 17-19, Dubrovnik, Croatia


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AGEDA

1.day - THURSDAY 17th

September 2009 (Invited lecture + methods presentations)

08:30 to 09:00: Arrival of partners, (Coffee break)

09:00 to 09:15: Welcome, introduction of workshop contents (V. Zanic, I. Grubisic (Dean) UZ)

09:15 to 10:00: Overview of IMPROVE project (Ph Rigo-ANAST)

10:00 to 10:45: Invited lecture 1: Lecture on rational structural design methodology (O.F. Hughes,

Virginia Tech.)

10:45 to 11:15: Coffee break

TOOLS FOR EARLY DESIG STAGE- BLOCK 1 - Modules

11:15 to 12:15: WP 3- Modules for the structural response and load calculation (UZ+ WP3 partners)

12:15 to 12:45: Panel discussion

12:45 to 14:00:LUNCH

TOOLS FOR EARLY DESIG STAGE- BLOCK 2 - Modules

14.00 to 15:00: WP4- Production & operational modules (CMT/NAME + WP4 partners)

15.00 to 15:30: Panel discussion15:30 to 16:00: Coffee break

TOOLS FOR EARLY DESIG STAGE- BLOCK 3 Integration &Tools

16:00 to 16:15: Integration platform of IMPROVE project (USCS, BAL)

16:15 to 16:45: Tools presentation: LBR5 software (ANAST)

16:45 to 17:15: Tools presentation: OCTOPUS/MAESTRO software (UZ)

17:15 to 17:45: Tools presentation: CONSTRUCT software (TKK)

19:15 to 20:00: Cocktail in Maritime Museum of Dubrovnik

20:00: Boat trip to Cavtat, Dinner


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I

TABLE OF CONTENTS

IMPROVE PROJECT OVERVIEW

IMPROVE - Design of Innovative Ship Concepts using an Integrated Decision

Support System for Ship Production and Operation 2

Philippe Rigo - ANAST, University of Lige

INVITED LECTURERS

Next Generation Ship Structural Design 20

Owen F. Hughes, Virginia Tech.

Ship Design for Performance 26

Kai Levander - SeaKey Naval Architecture

METHODS and TOOLS

Tools for Early Design Stage - Modules for the Structural Response and

Load Calculations (WP3)

New and Updated Modules to Performed Stress and Strength Analysis 37

V. Zanic, T.Jancijev, J. Andric, M. Grgic, S. Kitarovic, P.Prebeg - University of Zagreb,


P. Rigo, C. Toderan, D. Desmidts, A. Amrane, T. Richir, E. Pircalabu - ANAST, University

of Liege

M. Lappy - DN&T

Local and global ship vibrations 41

A. Constantinescu & Ph. Rigo -University of Lige

I. Chirica, S. Giuglea& V.Giuglea -Ship Design Group

Assessment of ultimate strength at the early design stage 46

H. Naar and M. Mesalu - MEC-Insenerilahendused

S. Kitarovic, J. Andric and V. Zanic - University of Zagreb, Faculty of Mechanical Engineeringand Naval Architecture

Rational models to assess fatigue at the early design stage 50

H. Remes, M. Liigsoo - Helsinki University of Technology

A. Amrane - ANAST University of Lige

I. Chirica, V. Giuglea, S. Giuglea - Ship Design Group

Sloshing Loads to be Applied on LNG Carriers Inner Hull Structure 53

L. Diebold, N. Moirod & Ph. Corrignan - Bureau Veritas


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II

Tools for Early Design Stage - Production, Operational and Robustness

Modules (WP4)

Production, Operation and Robustness Module 55

J.D. Caprace, F. Bair - ANAST University of Lige

M. Hbler - Center of Maritime Technologie

I. Lazakis, O. Turan - NAME Universities of Glasgow & StrathclydeV. Zanic, J. Andric, P. Prebeg, K. Piric - University of Zagreb

The effect of increasing the thickness of the ships structural members on the

Generalised Life Cycle Maintenance Cost (GLCMC) 61

I. Lazakis, O. Turan - NAME Universities of Glasgow & Strathclyde

Tools for Early Design Stage - Integration and Tools

Software integration in the context of the IMPROVE project (WP5) 68

S. Wurst & M. Lehne - BALance Technology Consulting GmbH

B. Cupic - Uljanik Shipbuilding Computer Systems d.o.o.

Tools for early design stage: presentation of LBR-5 Software 71

Ph.Rigo, F.Bair, Caprace J., D.Desmidts, A.Amrane, A.Constantinescu, R.Warnotte -

ANAST University of Lige

A.Hage, E.Pircalabu, M.Lapy - DN&T

Tools for early design stage: OCTOPUS and MAESTRO Software 74

V.Zanic, J.Andric, M.Stipcevic, P.Prebeg, S.Kitarovic, M.Grgic, K.Piric, N.Hadzic -University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture

ConStruct - Platform for Conceptual Structural Design 80

H. Remes, A. Klanac, P. Varsta, S. Ehlers - Helsinki University of Technology

APPLICATION CASES

Product Presentation: LNG Carrier (WP6)

LNG Carrier Ship Owner requirements, markets and technical trends 85F. Van Nuffel - EXMAR

An innovative LNG Carrier 87

L. Claes - STX Europe

J.-L. Guillaume-Combecave - STX Europe

LNG carrier- Structural design aspects 90

A. Amrane, A. Constantinescu, F. Bair and P. Rigo - ANAST, University of Liege

V. Zanic, J. Andric, N. Hadzic - University of Zagreb, Faculty of Mechanical Engineering and

Naval Architecture


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III

LNG carrier new innovative product 96

A. Constantinescu & Ph. Rigo - University of Liege

J.-L. Guillaume Combecave - STX-Europe

Product Presentation: ROPAX Ship (WP7)

ROPAX Carrier Ship Owner requirements, markets and future trends 100

Dario Bocchetti - Grimaldi Group

New innovative ROPAX vessel 102

. Dundara, O. Kuzmanovi- Uljanik Shipyard

V. Zanic, J. Andric, P. Prebeg, N. Hadzic - University of Zagreb, Faculty of Mechanical

Engineering and Naval Architecture

RoPaX- Structural design aspects 107

V. Zanic, J. Andric, P. Prebeg, M. Stipcevic, M. Grgic, S. Kitarovi, N. Hadzic, K. Priric -

University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture

I. Chirica, S. Giuglea & V. Giuglea - Ship Design Group

O. Turan, H. Khalid - NAME Universities of Glasgow & Strathclyde

P. Rigo - ANAST, University of Liege

Product Presentation: Chemical Tanker (WP8)

The IMPROVEd chemical tanker: Owner requirements 115

A. Klanac - Helsinki University of Technology

M. Maga, Z. Brzi, I. Pupovac - Tankerska plovidba Zadar

The basic design, performance and stability of the IMPROVEd chemicaltanker 119

S. Ehlers - Helsinki University of Technology

K. Kapucik - Szczecin New Shipyard

H. Khalid, O. Turan - University of Glasgow & Strathclyde

The IMPROVEd chemical tanker 123

S. Ehlers, A. Klanac, H. Remes - Helsinki University of Technology

K. Kapucik - Szczecin New Shipyard

H. Naar - MECJ. Andric, V. Zanic, M. Grgic - University of Zagreb

E. Pircalabu - Design Naval & Transport

F. Bair - ANAST, University of Liege

CONCLUSIONS

Final Conclusions of Workshop 132


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EU FP6 project IMPROVE-Final Conference IMPROVE 2009, Dubrovnik, CROATIA, 17-19 Sept. 2009 Page 1

IMPROVE PROJECT OVERVIEW


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EU FP6 project IMPROVE-Final ConferenceIMPROVE 2009, Dubrovnik, CROATIA, 17-19 Sept. 2009

IMPROVE - Design of Innovative Ship Concepts using an Integrated

Decision Support System for Ship Production and Operation

Philippe Rigo, ANAST,Univ. of Lige, [email protected]

IMPROVE coordinator

SHORT ABSTRACT: The EU FP6-IMPROVE Project proposes to deliver an integrated decision support system for amethodological assessment of ship designs to provide a rational basis for making decisions pertaining to the design,

production and operation of three new ship generations (LNG, RoPax, chemical tanker). These ship designs enhance theimportance of early stage structural optimization and integrated design procedure, which contribute reducing the life-cyclecosts and improving the performance of those ship generations.

ABSTRACT: IMPROVE has aimed to use advanced synthesis and analysis techniques at the earliest stage of the designprocess, considering structure, production, operational performance, and safety criteria on a current basis. The nature ofshipbuilding in Europe is to build small series of specialised ships. Thus, the IMPROVE project has addressed ships which,with their complex structures and design criteria, are at the top of the list for customisation.

The specific objectives of the project have been to:

develop improved generic ship designs based upon multiple criteria mathematical models improve and apply

rational models for estimation of the design characteristics (capacity, production costs, maintenance costs,availability, safety, reliability and robustness of ship structure) in the early design phase

use and reformulate basic models of multiple criteria ship design, and include them into an integrated decisionsupport system for ship production and operation.

The operatorsbuying specialised ships generally plan to operate them for the majority of their lives. This means that themaintenance characteristics of the design are very important and for this reason, IMPROVE has focused on designing for areduction in operation costs. Designing ship structures in such a way as to reduce the problems, for instance, of structuralfatigue can help in this cause. Additionally, designing for minimal operational costs can help in increase the structuralreliability and reduction of failures thus increasing safety.

The targets have been to increase shipyard competitiveness by 10% to 20% and reduce manufacturing costs by 8%-15%,production lead-times by 10%-15%, and to find benefit of 5%-10% on maintenance costs related to structure (painting,corrosion, and plate replacement induced by fatigue).

Front and centre of the IMPROVE project, however, has been the three specific ship types selected for the study.

The first of these is a 220 000m3: capacity LNG Carrier with free ballast tanks, designed by STX-France S.A.

The second ship type is a large Ro-Pax ship, with capacity for 3000 lane metres of freight and 300 cars, plus 1600passengers, with design by Uljanik Shipyard (Croatia).

The third ship is a 40,000dwt chemical tanker, designed by Szczecin Shipyard (SSN, Poland).


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IMPROVE - Design of Innovative Ship Concepts using an Integrated Decision Support System for Ship Production andOperation


1 INTRODUCTION

IMPROVE, http://www.improve-project.eu, is athree-year research project (2006-2009) supported by theEuropean Commission under the 6thFramework Programme

(Annex 1). The main goal of IMPROVE is to perform newinnovative ship designs (called products):

LNG Carrier, Fig.1 STX - Europe has designed andbuilt 17 LNG carriers (from 50 000 m3 to latest 154 500m3). In the framework of IMPROVE, they studied thedesign of a 220 000 m3unit with free ballast tanks to fulfillthe shipowner requirements and reducing the life-cyclecosts.

Large RoPax ship, Fig.2 - ULJANIK Shipyard (Croatia)in the last 5 years has designed several car-carriers, ConRo

and RoPax vessels. For a long period. ULJANIK has astrong cooperation with the GRIMALDI GROUP asrespectable ship owner regarding market needs and trends.

Chemical tanker, Fig.3 - SZCZECIN shipyard (SSN,Poland) has recently built several chemical tankers (40000DWT) and developed in the framework of IMPROVE a newgeneral arrangement of chemical tankers , saving productioncost by reducing amount of duplex steel and usingextensively corrugated bulkheads.

As the proposed methodology is based on multi-criteriastructural optimization, the consortium contains not onlydesigners, but also shipyards and ship-owners / operators(one per product). The research activity was divided in threemain phases:

Definition of stakeholders requirements andspecification of optimization targets and key performanceindicators. In addition, project partners (particularly theshipyards) designed reference or prototype ships, one pereach ship type, in a first design loop.

Technical and R&D developments relating to theselected structural optimization tools. Several modules suchas fatigue assessment, vibration, ultimate strength, sloshingload assessment, production and maintenance cost,optimization robustness have been delivered and most of

them integrated into these existing tools (LBR5, OCTOPUS,and CONSTRUCT).

Application of the developed optimization platforms forthe three target products.

The applications are described in detail for the LNGCarrier in Toderan et al. (2008) and in IMPROVE-RINA(2009), the RoPax ship in Dundara et al. (2008) and inIMPROVE-RINA(2008), and the chemical tanker in Klanacet al. (2008).

Figure 1. 220 000 m3 LNG carrier studied by STX- France

Figure 2. RoPax vessel designed by ULJANIK Shipyard (Croatia)


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Figure 3. 40 000 DWT chemical tanker by SSN (Poland)

2 PROJECT OBJECTIVES

2.1 The background

The IMPROVE project focuses on developing and

promoting concepts for one-off, small series and masscustomization production environments specific toEuropean surface transport, based on the innovative use ofadvanced design and manufacturing. The objective is toincrease shipyard competitiveness through improved

product quality and performance based on cost effective andenvironmentally friendly production systems on a life-cycle

basis. Target is to increase the shipyard competitiveness.Research seeks to reduce manufacturing costs, productionlead-times and maintenance costs of the ship structure.

The main objective is to design three different types ofnew generation vessels by integrating different aspects ofship structural design into one formal framework. Thenature of shipbuilding in Europe is to build small series ofvery specialized ships. Following this, IMPROVEconsortium identified next-generation prototypes of a largeRoPax ship, a product/chemical carrier and an LNG carrierwith reduced ballast tanks as the most suitable vessels tostudy (see Annex 1).

The operators using these ships generally operate themfor the most of the ships life, making maintenance

characteristics of the design very important. Therefore,IMPROVE aimed to design for lower operation costs.Designing ship structure in such a way as to reduce

problems such as fatigue can help in this cause.Additionally, designing for minimal operational costs helpsto increase structural reliability and reduction of failuresthus increasing safety.

The full life-cycle design approach is the key issue infuture design of ship structures. So IMPROVE proposescoupling of decision-support problem (DSP) environments(multi-attribute and multi-stakeholder concurrent design

problem) with life-cycle analysis, while deploying modernadvanced assessment and design approaches. Ship-owners

want to minimize short term investments but above allmaximize their long term benefits. Currently however,design of ships considers the life-cycle costs withlimitations, thus opening doors for significant improvementswith respect to ships economics and her competitiveness.

Formal integration of the life-cycle cost in the designprocedure and creating a long-term competitive ship couldbe used as a valid selling argument.

An integrated decision support system (DSS) for thedesign of ship structures can assist designer in challenging

this task. This novel design approach considers theusual technical requirements, but also producibility,

production cost, risk, performance, customer requirements,operation costs, environmental concerns, maintenance andthe life-cycle issues. IMPROVE has developed this newdesign environment. The purpose is not to replace thedesigner but to provide experienced designers with betterinsight into the design problem using advanced techniquesand tools, which give quantitative and qualitativeassessment on how the current design satisfies allstakeholders and their goals and requirements.

Keeping in mind that IMPROVE focuses on theconcept/preliminary design stage, since the mainfunctionally and technologically driven parameters aredefined in the concept design stage.

2.2 Scientific and technological objectives of theproject

In order to improve their competitiveness, the Europeanshipbuilding industry and ship-owners/operators needdevelopment of new generations of ships (products) for themost valuable and significant transportation needs:

- multimodal transport of goods (advanced genericRoPax),

- transport of energents (gas, oil)/chemicals(advanced gas carriers and chemical tankers).

- This should be achieved through the application of:


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- multi-stakeholder and multi-attribute designoptimization

- risk-based maintenance procedures,- manufacturing simulation,- and immediately used in the practice for ship

design, production and operation.Motivation came also from the fact that the IMPROVE

members were surprised by the constant quest forrevolutionary products, while the wisdom of quality productimprovement based on the mature design procedures wasnot been properly harvested. For example, by usingadvanced optimization techniques, significant improvementsin the design and production are available but still not used.

Now the feasibility of such potential improvements havebeen proved and confirmed owing to the three practical ship

designs done by IMMPROVE, i.e:

- Early definition of requirements and measures ofdesign quality:

- Generation of sets of efficient competitive designsand displaying them to the stakeholders for the finaltop-level selection.

- Selection of preferred design alternatives bydifferent stakeholders, exhibiting measurable andverifiable indicators, defined as Key PerformanceIndicators (KPI). At the start of the IMPROVE

project, it was expected that the generated designalternatives will experience the followingimprovements:o Increase in carrying capacity of at least 5% of

the steel mass (about 15% may be expected fornovel designs) compared to design obtainedusing classical methods,

o Decrease of steel cost of at least 8% (and morefor novel designs) compared to the designobtained using classical methods,

o Decrease of production cost corresponding tostandard production of more than 8-10% and

even more for novel designs,o Increase in safety measures due to rational

distribution of material and a priori avoidanceof the design solutions prone to multimodalfailure,

o Reduced fuel consumption,o Improved operational performance and

efficiency, including a benefit on maintenancecosts for structure (painting, corrosion,

plate/stiffener replacement induced by fatigue,etc.) and machinery.

Now, the project is over. Even if all these objectiveshave not been reached, a significant part has been achieved(see here after).

2.3 Long-term benefit of IMPROVE

The long-term goal of the project is to improve designmethodology by concentrating effort on advanced synthesisskills rather than improving multiple complex analyses. Ithas been shown that the structural design must integratevarious technical and non-technical activities, namelystructure, performance, operational aspects, production, andsafety. Otherwise, it is highly possible to define a shipdesign which is difficult to produce, requires high amountsof material or labor, contains some design flaws, or may benot cost-effective in maintenance and operation.Additionally, ships can be robust, with high performance in

cost and customer requirements criteria.

2.4 The IMPROVE Methodology

IMPROVE is based on existing design platforms andanalytical tools, which allow partners to use simulation andvisualization techniques to assess ship performance acrossits lifecycle. IMPROVE has implemented in these platformsan advanced decision support system (includingoptimization capabilities) by coupling the decision-baseddesign (multi-attribute and multi-stakeholder concurrentdesign problem) with the life-cycle analysis.

3 FUNDAMENTAL DESIGN SUPPORTSYSTEMS IN IMPROVE

The following three design support systems (DSS) areused in IMPROVE:

The LBR5 software is an integrated package to performcost, weight and inertia optimization of stiffened shipstructures, Rigo (2001, 2003), Rigo and Toderan (2003),allowing:

- a 3D analyses of the general behavior of thestructure (usually one cargo hold);

- inclusion of all the relevant limit states of thestructure (service limit states and ultimate limitstates) in an analysis of the structure based on thegeneral solid-mechanics;

- an optimization of the scantlings (profile sizes,dimensions and spacing);

- a production cost assessment considering the unitaryconstruction costs and the production sequences inthe optimization process (through a production-

oriented cost objective function);


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LBR5 is linked with the MARS (Bureau Veritas) tool.MARS data (geometry and loads) can be automatically usedto establish the LBR5 models.

Only basic characteristics such as L, B, T, CB, the globalstructure layout, and applied loads are the mandatory

required data. It is not necessary to provide a feasible initialscantling. Typical CPU time is 1 hour using a standarddesktop computer.

MAESTRO software combines rapid ship-oriented shipstructural modelling, large scale global and fine mesh finiteelement analysis, structural failure evaluation, and structuraloptimization in an integrated yet modular software package.Basic function also include natural frequency analysis, bothdry mode and wet mode. MAESTROs core capabilitiesrepresent a system for rationally-based optimum design of

large, complex thin-walled structures. In essence,MAESTROis a synthesis of finite element analysis, failure,or limit state, analysis, and mathematical optimization, all ofwhich is smoothly integrated under an ease-of-use of aWindows-based graphical user interface for generatingmodels and visualizing results.

OCTOPUS is a concept design tool developed withinMAESTRO environment, Zanic et al. (2002, 2004).Concept design methodology for monotonous, tapered thin-walled structures (wing/fuselage/ship) is including modulesfor: model generation; loads; primary (longitudinal) andsecondary (transverse) strength calculations; structuralfeasibility (buckling/fatigue/ultimate strength criteria);design optimization modules based on ES/GA/FFE;graphics.

CONSTRUCT is a modular tool for structuralassessment and optimization of ship structures in the earlydesign stage of ships. It is primarily intended for design oflarge passenger ship with multiple decks and large openingsin the structure. It is also applicable for ships with simplerstructural layouts as those tackled in IMPROVE.

CONSTRUCT can generate a mathematical model of theship automatically, either through import of structuraltopology from NAPA Steel or the topology can be generatedwithin CONSTRUCT.

CONSTRUCT applies the method of Coupled Beams,Naar et al. (2005), to rapidly evaluate the structuralresponse, fundamental failure criteria, i.e. yielding,

buckling, tripping, etc., and omni-optimization procedurefor generation of competitive design alternatives, Klanacand Jelovica (2007). CONSTRUCT at the moment canapply VOP algorithms to solve the optimization problem,Klanac and Jelovica (2009).

The philosophy behind CONSTRUCT is outmostflexibility. Therefore, it can concurrently tackle largenumber of criteria, either considering them as objectives orconstraints, depending on the current user interests. Designvariables are handled as discrete values based on the

specified databases, e.g. table of bulb profiles, stock list ofavailable plates, etc. Also, new computational modules canbe easily included, e.g. to calculate crashworthiness ofships.

4 CONTRIBUTION TO ENHANCING THESTATE-OF-THE-ART IN SHIPSTRUCTURE OPTIMIZATION

4.1 Enhancement of the rational ship structure

synthesis methods and DSP approaches

IMPROVE has developed new mathematicaloptimization methods. IMPROVE focused on the DSS

based approach to the design of ship structures and not onsearch algorithms. IMPROVE aimed for more efficient useof the available optimization packages and their integrationin the design procedure. IMPROVE focused on themethodology/procedure that a designer and shipyard shouldfollow to improve efficiency in designing, scheduling and

production of ships. This methodology was used to inhancethe link between design, scheduling and production, withclose link to the global cost. IMPROVE has confirmed thatit is only through such integration that specific optimizationtools can be proposed to shipyards to improve their globalcompetitiveness.

4.2 Enhancement of particular multidisciplinary

links in the synthesis models

The IMPROVE DSS-based approach has enhanced:

- Link of design with maintenance and operationalrequirements which may differ from the shipyardinterest

- Link of design procedure with productionthrough an iterative optimization procedure

- Link of design procedure with cost assessmentand therefore drive the design to a least-cost design(or a least weight if preferred)

- Link of production with simulation andtherefore drive the design to a higher laborefficiency and a better use of man-power and

production facilities


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4.3 Enhancement of confidence in the structural

DSS approaches through the development of

three innovative ship products

IMPROVE has enhanced the present design procedurestate-of-art using new improved synthesis models and has

- demonstrated the feasibility on an increase of theshipyard competitiveness by introducing multi-disciplinary optimization tools,

- demonstrated acceleration of the design procedureby using integrated tool such as LBR5,

- Proposed new alternatives to designs that may ormay not fit with standards and Class Rules. Suchrevised designs have to be considered by thedesigners as opportunities to reconsider the

problem, its standards and habitudes, to think about

the feasibility of alternative solutions, etc.- validated newly developed design approach tested

on three real applications (RoPax, LNG carrier,chemical tanker) by associating a shipyard, aclassification society, a ship owner and a university.

- enhanced modeling of advanced structural problemsin the early-design optimization tools (e.g.crashworthy hull structure, ultimate strength,vibration, fatigue limit state in structures, sloshingload).

5 RESEARCH WORKS PERFORMEDWITHIN IMPROVE

IMPROVE includes 7 inter-dependent work packages(WP2-WP8). The schematic representation of these WPswith the exchanges of information/data is shown in Fig. 4.

Figure 4. The IMPROVE flowchart

5.1 Problem & Model Definition (WP2)

In WP2, the consortium defined the structure of the

integrated framework for design of ship structures toincrease the functional performance and to improvemanufacturing of those designs. The core of this WP was toidentify rational decision making methods for the use in thedesign of ship structures within the shipyard environment.

Figure 4. The IMPROVE flowchart

- Specific objectives of this work package were:- Definition of the multi-stakeholder framework in

design of ship structures,- Definition of particular interests of stakeholder for

the specific application cases,- Definition of design criteria (objectives and

attributes), variables and constraints,- Identification and selection of methods to solve the

structural, production and operational issuesaffecting design,

- Synthesis of needed actions into a framework.

One of the significant and valuable results of IMPROVE

is the extensive list of design objectives and design variablesselected for the concerned ships (which has been published

by the ISSC international scientific association). Qualitymeasures, key performance indicators and potential selectedtools were also listed.

5.2 Load & Response Modules (WP3)

In WP3 the load and response calculation modules wereidentified. These modules were selected and upgraded to fitwith the design problems and design methods identified inWP2. For instance with the 11 loads and response modules

identified in WP3, there are:

- Response calculations for large complex structuralmodels, including equivalent modeling

- Very fast execution of numerous safety criteriachecks, including ultimate strength, vibration, basedon library of various modes of failure undercombined loads.

- Module accommodation for calculation of structuralredundancy, vibration and stress concentration forfatigue assessment.


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5.3 Production & operational modules (WP4)

A new module for tankers was developed to assess thelife cycle impacts, applying simple and advanced existingtools, Rigo (2001), Caprace et al. (2006). The WP taskscontained the following activities:

- Implementation of a operation and life-cycle costestimator for tanker vessels,

- Implementation of a production simulation to assessthe impact of different design alternatives on thefabrication,

- Implementation of a production cost assessmentmodule to calculate of workforces needed for eachsub assemblies used inside the productionsimulation.

In the framework of IMPROVE all these tools wereintegrated into the global decision tools.

5.4 Modules Integration (WP5)

Main features of the IMPROVE Integration Platform

are:

- A design desktop as central component and controlcentre,

- All calculations can be initiated and their results canbe stored project-wise,

- Iterations and comparisons will be supported,- Applications and file exchange organized based on

workflow definition..

Figure 5. The IMPROVE optimization approach

As MARS-BV is used by most of the partners, theMARS-BV database becomes the reference data concerninggeometry and loads. This means that all the moduleinterfaces (fatigue, vibration, cost, ) have considered theMARS data as reference data, Fig.5. Of course, additionalspecific data were required to make the link with theoptimization tools (LBR5, CONSTRUCT, OCTOPUS)

6 LNG Carrier An innovative concept for alarge liquefied natural gas carrier (LNGC)

A new forward-looking design for a 220,000m3capacityliquefied natural gas carrier (Fig 6) has emerged as part ofthe EU-funded IMPROVE project, following a study bySTX France S.A.

Over recent years, the Saint-Nazaire shipyard (formerlyChantiers de lAtlantique), currently STX France S.A., has

designed and built several LNG carriers for differentshipowners implementing innovative ideas such as the first

diesel-electric dual-fuel LNG carrier. Continuing a longtradition of innovation, the French shipyard proposes oncemore a new design concept for liquefied natural gas carriers.

The Saint-Nazaire shipyards designers propose asolution to reduce the need for ballasting in order to prevent

biological invasions of marine organisms transported in

ballast water and sediment transfer. Moreover, energy andthus money will be saved by decreasing the huge amountsof sea water transported, almost unnecessarily.

As part of the IMPROVE project, STX France has beenmeticulous in addressing a host of vessel attributes that addup to a state of the art ship design for LNG transportation.

These range from ensuring the large cargo carryingcapacity within minimum dimensions, the observance of

best practice in shipbuilding, high levels of safety, economicfeasibility, low maintenance, high screw comfort, andsecurity in terms of environmental protection.

MARS - BV

FILE

LBR5 CONSTRUCT OCTOPUS-

MAESTRO

NEW IMPROVE MODULES

(Fatigue, Cost, vibration, )


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may also be considered, subject to further studies, according

to STX France.

Cargo containment

The proposed containment system is of the membrane

type, five (5) tanks based on Gas Transport and Technigaz(GTT) technology. Sloshing problems will be avoided by

following the GTT and classification society requirements.

The insulation of the cargo tanks has been designed to

give a natural boil-off-rate (BOR) to about 0.135 % (per

day) of the loaded cargo volume.

Other containment solutions with independent tanks

such as Aluminium Double Barrier Tank (ADBT) are

possible and adaptable to the ship design with further

studies.

The hull form is designed with more than 80 % of

developable surfaces, and minimizes the cost of production

of the hull.

For a conventional LNGC the exploitation conditions are

50 % of the time in a loaded condition and 50 % of the time

in an unloaded condition. For the STX France design, the

partition of the exploitation conditions are the same but,

within the unloaded condition, 80 % of the time only a

minimum volume of sea water is required, which may be

nil, and the remaining in considered with full SWBT.

Under such assumptions, around 8.6 tons of LNG used

as fuel can be saved par day. This is equivalent to a 9 %

saving when compared to a diesel electric dual fuel LNG

carrier with about the same size and conventional features.

STX France is currently designing other LNGC sizesuch as & medmax LNGC with the same principle.

Figure 7. The LNG with five cargo tanks, offering a large capacity of 220,000m3, with length limited to 319.

319.2

50 m


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Figure 10. Body Lines of New ROPAX Ship

The length of engine room was reduced (increased length

of cargo space). Small Main propulsion engine was chosen

which allows for a smaller engine room i.e. more cargo space

available. A comfort-friendly hull form and generalarrangement were designed. Various structural

arrangements were analyzed by the shipyards and

universities involved as a multi-objective design problem

i.e. accommodations - two and three tiers. Lower garage

breadths 15.36 m, 16.56 m and 17.76 m. The design with

two superstructure decks and additional car space was finally

selected (Version 2). In total number six ro-pax ship model

designs were investigated. Structural FEM optimization was

performed for three modules per model between frames 72

and 200. Optimization modules contained a total number of

9 decks for the first accommodation layout and 8 for the

second one. Only the 5thdeck was not modeled because it is

a mobile deck thus does not contribute in ships strength.Ramps linking decks were also not modeled. The lower

cargo hold is enclosed between transverse bulkheads at

frames 72 and 200, inner bottom and deck 3 and two

longitudinal bulkheads. Its height mainly depends on its

breadth (based on damage stability criteria). In the

conceptual design phase structural elements forming

longitudinal bulkheads between decks 6 and 9 (6 and 8 for

second layout) were ignored during the optimization.

Figure 11. IMPROVE RO-PAX deck arrangement (version 2)

Figure 12. Selected ship zone for structural optimization


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Figure 13. x stresses

Four load cases were defined for the FEM models,Figure 13, based on BV classification requirements

In terms of the propulsion system, two propulsionsystem options were the most suitable:

Option 1.

o A slow speed main engine directly coupled tofix pitch propeller.

o An active rudder/azipod with propulsion bulb toincrease main propeller efficiency.

Option 2o Two medium speed main engines coupled via

gearbox to CP-propeller.o Two retractable side thrusters.

The aim was to minimize the need of running ofelectrically driven thrusters in seagoing condition i.e. usethem only during manoeuvring in harbour to eliminate theneed for tugs. Thus obtain a 100% redundancy notation. Theowners basic requirement was that ship must never stop.The owners preferred the configuration of two main enginescoupled via gearbox to one CP-propeller (Option 2). Thisarrangement gives the ability to operate vessel with onemain engine running and carry out maintenance on the othermain engine.

CONCLUSIONS

An innovative ropax design has been created following a

multi-stakeholder approach where shipyards and ship-

operators were involved. Structural design satisfies BureauVeritas (BV) rules. To maximize the key performanceindicators (KPI) for a ropax product various aspects of shipstructural designs were integrated into the multi-criteriaoptimization process via several modern tools developedwithin IMPROVE EU project. The design was based on asuccessful existing design of a STANDARD SHIP used as a

prototype. The design has significant advantages ascompared with traditional ropax ships including improvedredundancy and simplicity of systems; manoeuvrability;optimised sea-keeping performance; maximised comfort andminimised vibrations. Following ship-owners feedback, thevessel was designed with an 8% increase in carryingcapacity (lane metres) on the tank top by decreasing thelength of the engine room. Within set requirements thedesign considered large variations in seasonal trade(summer 3000pax, winter 100pax).

8 CHEMICAL TANKER

The third product being developed under the IMPROVEproject is a chemical Tanker suitable to carry chemicalcargoes lMO type I/II/III, petroleum products, vegetableanimal and fish oils and molasses.

A new generation design of a 40,000dwt chemical tanker(Fig 14, Fig 15) has emerged as an outcome of theIMPROVE project. Advanced synthesis and analysistechniques at the earliest stage of the design process were

used considering structure, production, operationalperformance, and safety criteria on a concurrent basis.


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Figure 14. 40 000 DWT chemical tanker by SSN (Poland)

Figure 15.Body plan of IMPROVE Chemical Tanker

1) The first phase was attributed to the identification

of stakeholders requirements and the definition of

key performance indicators. The project partners

(particularly the shipyards) designed reference orprototype ships. As part of this phase, it was

realised that operators require ships with the

longest possible lifetime and that this can be

achieved by improving quality and performance.

The main design objectives were the reduction of

manufacturing costs and production lead-time as

well as the reduction in the structural maintenance

costs for ship owners. Several calculations were

performed to test existing tools and identify

potential gains at the conceptual stage of design.

2) The second phase was concerned with thedevelopment of new modules to be integrated in

the optimization tools in order to satisfy the

requirements defined in the first phase. All

technical developments were based on selected

structural optimization tools. Several modules suchas fatigue assessment, vibration level investigation,

ultimate strength, load assessment, production cost

and maintenance cost reduction were delivered and

integrated into existing tools e.g. LBR5,

OCTOPUS, CONSTRUCT, etc.

3) The final phase was the application of the new

(improved) optimization tools for the final

chemical carrier design. In brief IMPROVE

delivered an integrated decision support system for

a methodological assessment of ship designs. This

system provided a rational basis for makingdecisions regarding the design, production and


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operation of a highly innovative chemical carrier.This support system can be used make carefuldecisions that can contribute to reducing the life-cycle costs and improving the performance of aship. Based on this system all the aspects related to

the general arrangement, propulsion, hull shapeand dimensioning of the structure wereinvestigated.

The relation between structural variables and relevantcost/earning elements has been explored in detail. Thedeveloped model is restricted to the relevant life-cycle costand earning elements, namely production costs, periodicmaintenance costs, fuel oil costs, operational earnings anddismantling earnings. The maintenance/repair data werecollected from three ship operators and were used for the

purposes of a regression analysis. The design is based on a

multi-objective optimisation of the structure using guidedsearch versus conventional concurrent optimisation. Theresults of the adopted approach were compared with theconventional concurrent optimisation of all objectivesutilising genetic algorithm NSGA-II. The results showedthat the guided search brings benefits particularly withrespect to structural weight, which is normally a verychallenging parameter to successfully optimize.

IMPROVE partner shipyard based the design on areference design, the B588-III chemical carrier, aiming

mainly to achieve lower building costs. The followingalternatives of the reference design were considered:

Alternative 1

Main dimensions as in original design B588-III. Wing cargo tanks made of mild steel instead of

Duplex steel.

Reduction of number of centre cargo tanks fromeighteen to twelve.

Reduction of service speed to 15.0 kn. Not including a shaft generator.

Alternative 2

Reduction of cargo tanks capacity to abt. 45 000 m3. Removal of cofferdam bulkheads and replacing

them by vertically corrugated bulkheads.

Reduction of depth of the vessel to 15.0 m. Using of Duplex steel for centre tanks only. Removal of six deck tanks. Reduction of service speed to 15.0 kn. Not including a shaft generator.

Alternative 3

As Alternative 2 apart from the arrangement of Duplextanks which are arranged in the middle part of the vessel /wing and centre tanks.

Calculation of building costs done based on 2007 marketdata showed that the most effective cost reduction wasrealised adopting Alternative 3. Thus the partners decided todevelop this design and optimize it using IMPROVE tools.The seakeeping analyses, based on this design, indicatedthat in general, the vessel is expected to exhibit goodseakeeping characteristics as most of the worst responsemodal periods are either far off from the dominant wave

periods or wave headings may be adjusted to avoid severeresponses. A thorough fatigue analysis was implemented.The hull optimization resulted in significant production costreduction. Life cycle costs were also assessed

Figure 16. Structural assessment of the Chemical Tanker


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Analyses also showed that the IMPROVE ChemicalTanker satisfies the stability requirements of applicablerules and regulations (Figs 16 and 17).

For the optimization of cargo tank arrangement the maintarget was to reduce the quantity of Duplex steel to

minimize cost. For the final design the total optimumnumber of Duplex stainless steel tanks is eighteen withvarying capacities. Duplex stainless steel cargo tanks areseparated from the mild steel cargo tanks by cofferdams.

Moreover longitudinal bulkheads are vertically corrugatedand transverse bulkheads may be vertically or horizontallycorrugated. Interfaces between longitudinal verticallycorrugated bulkheads and transverse horizontally corrugated

bulkheads were subjected to FEM analyses.

Calculations of cargo tanks capacity and arrangement forthree different specific gravities of acid 1.50, 1.65, and 1.85t/m3have been performed

.

Figure 17.3D Model of the Chemical Tanker

The propulsion system consists of a low speed twostroke diesel ME driving directly FP propeller at servicespeed to be 15.0 kn. Three types of main engines have beenevaluated:

5S60 - MC - C7,6S50 - ME - B9,6S50 - ME - B8.

Main engine type 6S50 - ME -B9 was chosen for thechemical carrier design.

9 CONCLUSIONS

This introductive paper of the IMPROVEDUBROVNIK workshop (Sept 209) introduces theobjectives of the IMPROVE FP6 project, its methodologyand the three innovative ships developed from 2006 to 2009

by multidisciplinary teams of researchers (shipyard,shipowner, designer, classification society and university).

This paper presents briefly the 3 product, given theirspecific objectives and the main outcomes. More detailedinformation are available in the companion papers also

presented at this Dubrovnik workshop.

In short, main outcomes of the IMPROVE projects are:

The design by STX France of a new concept of LNGcarriers with reduced ballast, that provides a significant

benefit for the shipowners. In addition, a weight saving of10-15% has been identified and a reduction of productioncost of 5% is also reached.

The design by Uljanik Shipyard (Croatia) of animproved ROPAX, with reduced fuel consummation due tonew Ropax propulsion concept. The structural optimisationhas also show a significant reduction of the weight for aimproved safety with regards to the BV classificationsociety requirements.

The design of a new general arrangement of a chemicaltanker including, reduced weight of duplex steel, intensive


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use of corrugated bulkhead, for a improved safety withregards to the classification society requirements.

Detailed conclusions with quantitative assessment of thebenefits of the three new IMPROVE concepts are given inthe Dubrovnik papers dedicated respectively to the LNG,

ROPAX and Chemical Tanker.

ACKNOWLEDGEMENTS

The present paper was supported by the EuropeanCommission under the FP6 Sustainable Surface TransportProgramme, namely the STREP project IMPROVE (Designof Improved and Competitive Products using an IntegratedDecision Support System for Ship Production andOperation) - Contract No. FP6 031382. The EuropeanCommunity and the authors shall not in any way be liable or

responsible for the use of any such knowledge, informationor data, or of the consequences thereof.

REFERENCES

CAPRACE, J.D.; RIGO, P.; WARNOTTE, R.; LE VIOL, S.(2006), An analytical cost assessment module for thedetailed design stage, COMPIT2006, Oegstgeest,

pp.335-345DUNDARA, D.; BOCCHETTI, D.; KUZMANOVIC, O.;

ZANIC, V.; ANDRIC, J., PREBEG, P. (2008),Development of a new innovative concept of RoPax ship,COMPIT2008, Edit. Rigo-Bertram, Univ. of Liege,

Belgium, ISBN-10 2-9600785-0-0IMPROVE RINA (2008),RO-RO Technology, Building toImprove Sandards, The Naval Architect, April 2008

IMPROVE RINA (2009), Move to IMPROVE LNGCarrier Design, The Naval Architect, May 2009

KLANAC, A.; JELOVICA, J. (2007), A concept of omni-optimization for ship structural design, Advancements inMarine Structures, Proceedings of MARSTRUCT 2007,

1st Int. Conf. on Marine Structures, Glasgow, UK.,Guedes Soares & Das (eds), Taylor & Francis: London,

pp.473-481KLANAC, A.; JELOVICA (2009), J. Vectorization and

constraint grouping to enhance optimization of marinestructures, Marine Structures, Volume 22, Issue 2, pp225-245

KLANAC, A.; NIEMELINEN, M.; JELOVICA, J.;REMES, H.; DOMAGALLO, S. (2008), Structuralomni-optimization of a tanker, COMPIT2008, Edit.Rigo-Bertram, Univ. of Liege, Belgium, ISBN-10 2-9600785-0-0

MAESTRO Version 8.5 (2005), Program documentation,Proteus engineering, Stensville, MD, USA

NAAR H.; VARSTA, P.; KUJALA, P. (2004), A theory ofcoupled beams for strength assessment of passengerships, Marine Structures 17(8), pp.590-611

RIGO, P. (2001), Least-cost structural optimizationoriented preliminary design, J. Ship Production, 17/4,

pp.202-215

RIGO, P. (2003), An integrated software for scantlingoptimization and least production cost, Ship TechnologyResearch 50, pp.126-141

RIGO P.; TODERAN, C. (2003), Least cost optimisation ofa medium capacity gas carrier, COMPIT03, Hamburg,

pp.94-107TODERAN, C.; GUILLAUME-COMBECAVE, J.L.;

BOUCKAERT, M.; HAGE, A.; CARTIER, O.;CAPRACE, J.D.; AMRANE, A.; CONSTANTINESCU,PIRCALABU, E.; A.; RIGO, P. (2008), Structuraloptimization of a 220000 m3 LNG carrier,COMPIT2008, Edit. Rigo-Bertram, Univ. of Liege,Belgium, ISBN-10 2-9600785-0-0

ZANIC, V.; ROGULJ, A.; JANCIJEV, T.; BRALI, S.;HOZMEC, J. (2002), Methodology for evaluation ofship structural safety, 10th Int. Congress IMAM 2002,Crete

ZANIC, V.; PREBEG, P. (2004), Primary responseassessment method for concept design of monotonousthin-walled structures, 4th Int. Conf. on AdvancedEngineering Design, Glasgow, pp.1-10


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INVITED LECTURERS


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EU FP6 project IMPROVE-Final ConferenceIMPROVE 2009, Dubrovnik, CROATIA, 17-19 Sept. 2009

Next Generation Ship Structural Design

Owen F. HughesVirginia Tech., Blacksburg, Virgina, USA

ABSTRACT: Ship structural design continues to pose challenges for the design team to effectively address inherentcomplexities, evolving performance requirements from owners and regulators, and need for efficient integration with theoverall ship design process. Next generation ship structural design tools and methods must further unify structural design

process sub-elements into a more efficient and higher fidelity process that supports the realization of engineering integritywith optimized performance for the owner/operator. Advances in design tool architecture, geometry and topology modeling,

loads analysis, and structural evaluation must be better unified in order to achieve progress toward these objectives. Thepaper gives some examples and suggestions as to how these needs (more unity among the structural design process sub-elements and better integration with the overall ship design process) can be achieved.

1 INTRODUCTION

Ship structural design continues to pose challenges forthe design team to effectively address inherent complexities,evolving performance requirements from owners andregulators, and need for efficient integration with the overallship design process. Next generation ship structural designtools and methods must further unify structural design

process sub-elements into a more efficient and higherfidelity process that supports the realization of engineeringintegrity with optimized performance for theowner/operator. Advances in design tool architecture,geometry and topology modeling, loads analysis, andstructural evaluation must be better unified in order toachieve progress toward these objectives.

2 HISTORICAL PERSPECTIVE

In describing a vision of next generation ship structural

design from the vantage point of 2009, it is interesting toreflect on personal experience from a very different vantage

point, the 1970s. In the 1970s personal computers did notexist, and engineering design and analysis processes andtools were in the early days of transitioning to(mainframe) computer utilization. This was certainly thecase for ship structural design. The transition to computer

based methods offered opportunities to change thetraditional empirical approach for ship structural design to arational approach, which can be characterized by:

Design which is directly and entirely based on structuraltheory and computer-based methods of structural analysis

and optimization, and which achieves an optimum structureon the basis of a designer-selected measure of merit.

The vision of using the computer to implement andapply a rational approach for ship structural design becamethe focal point of my research. This visions approach wasto unify four technologies; structural analysis using thefinite element method, structural failure theory,

optimization, and the computer, into a methodology thatcould perform rationally-based ship structural design in pacewith the normal preliminary design process. This vision

was presented in (Hughes et al., 1980) and fullydocumented in Ship Structural Design (Hughes, 1983)and the vision was implemented at that time in the computer

program MAESTRO. Figure 1 highlights the overallmethodology of this implementation, including six basicaspects of rationally-based structural design. The approachimplemented in MAESTRO has been in practice since itsrelease in 1984 and has withstood many tests of time and

undergone many significant changes. Further, there areongoing and planned evolutionary developments thatconfirm the complexity of ship design and the need forcontinued development of the technology for rationally-

based design.


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MODELING OF LOADS

STRUCTURAL RESPONSE ANALYSIS

CALCULATE LOAD EFFECTS, Q

LIMIT STATE ANALYSIS

CALCULATE LIMIT VALUESOF LOAD EFFECTS, QL

OPTIMIZATION OBJECTIVE

1

OtherConstraints

YES

STOP

NO

Partial Safety

Factors 12 3

EVALUATION

(A) FORMULATE CONSTRAINTS (B) EVALUATE ADEQUACY

1 23 Q QL CONSTRAINTS SATISFIED?OBJECTIVE ACHIEVED?

2

3

4

56

Six Elements of Rationally -BasedShip Structural Design

All s ix are n ecessar y

All s ix must be balan cedand integrated

Figure 1. Six Basic Aspects of Rationally-Based Ship

Structural Design

3 SHIP STRUCTURAL DESIGN

EVOLUTIONSince the early manifestations of computer-based ship

structural design and rationally-based design, significantevolution has taken place and many improvements have

been developed. An overview of ship structural designevolution from Strength of Ships and Ocean Structuresfollows:

"The drive toward more efficient ship designs has led toincreased sophistication in both the designs themselves andin the techniques and tools required to develop the design.

Concepts such as finite element analysis, computationalfluid dynamics, and probabilistic techniques for evaluating aship's stability and structural reliability are now integral tothe overall design process. The classification societies havereleased the common structural rules for tankers and bulkcarriers, which rely heavily on first principles engineering,use of finite element analysis for strength and fatigueassessments, and more sophisticated approaches to analysissuch as are used for ultimate strength assessment for the hullgirder. The International Maritime Organization now relieson probabilistic approaches for evaluating intact and

damage stability and oil outflow. Regulations areincreasingly performance-based, allowing application ofcreative solutions and state-of-the-art tools. Riskassessment techniques have become essential tools of the

practicing naval architect." (Mansour and Liu, 2008)

The structural design technology evolution summarizedabove can be further defined in several categories:

Finite Element Analysis (FEA). Great strides havebeen made in FEA theoretical and computational technologyin both software and in computers, including reduction in

cost, increasing dramatically the application of FEA for shipstructural design.

Structural Limit State Evaluation.In the past, criteriaand procedures for the design of steel-plated structures were

primarily based on allowable stresses and simplifiedbuckling checks for structural components. However, it isnow well recognized that the limit state approach is a better

basis for design since it is difficult to determine the real

safety margin of any structure using linear elastic methodsalone. (Paik and Thayamballi, 2008) Limit state evaluationimprovements have been in the form of new theoryimplemented in practical codes/software, limits at both thestiffened panel level and at the hull girder level, andautomation in checking large numbers of panels for multipleload cases.

Optimization Methods and Tools.Multiple individualdecision support/optimization methods are now beingorganized into multi-criteria structural optimizationcapabilities that address design criteria (serviceability,

ultimate strength) and design quality (cost, weight,reliability, robustness) within an efficient system thatsupports global and local structural optimization.

Software Development Technology and

Environments.Continuous change and evolution has takenplace in the languages, tools, and development and datamanagement environments used to design and implementship structural analysis codes. These improvements enablemore robust tool development, facilitate code change andevolution, and support broader integration of structural

design tools with other disciplines of the ship design such astopological modeling and loads analyses.

Collectively, the progressive evolution of thesetechnologies and tools have dramatically changed theapproach to ship structural design, and yet many newdevelopments continue today and for the foreseeable future.

4 NEXT GENERATION SHIPSTRUCTURAL DESIGNREQUIREMENTS

Figure 2 illustrates the relationship between the earlystage concept development of a ship and the ability toinfluence the life-cycle performance in terms of operational

performance, cost and other factors. The influence ishighest early in the design development and rapidlydiminishes as the design matures toward start of lead shipconstruction. Figure 2 (Wheelwright and Clark, 1995) alsohighlights the interaction that takes place, with varyingdegrees of completeness and accuracy, between the shipowners and operators, who determine the requirements and

budgetary bounds of the ship, and the design developers.


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Index of

Lifecycle

Influence

Design Space Exploration Strategy

Manu

factu

ring

Ramp

-Up

Low

Program L ife-Cycle Phases

Know

ledg

e

Acquisiti

on

Conc

ept

Inve

stiga

tion

Basic

Design

Prototyp

e

Build

ing Pi

lot

Prod

uctio

n

ABILITY TO INFLUENCE

LIFECYCLE OUTCOME

High

ACTUAL MANAGEMENT ATTENTION PROFILE

Design

SpaceExploration

Ship

Owner/

Operator

COST/

ROI

REQTS

Source: "Leading Product DevelopmentWheelwright & ClarkHarvard Business School

Index of

Management

Attent ion

Low

High

Figure 2. Design Space Exploration

A critical characteristic of the ship design process is thefrequency and accuracy with which the design team can

report back to the owner/operators to provide a descriptionof the design and its performance and cost attributes. Sincestructure is a major contributor to the construction cost andto the operational and financial performance of the ship,improved knowledge and accuracy of the ships structure isa critical factor in the development of the design.

This paradigm of ship design development translatesinto a movement toward accomplishing higher degrees of

physics-based engineering analysis and design as early inthe design process as possible. Figure 3 (Wood, 2007)illustrates the relationship between computer aidedengineering (CAE), which includes structural analysis anddesign, and computer aided design (typically the hull formand arrangements) and computer aided manufacturing(planning construction processes). Figure 3 highlights theneed to move CAE activities earlier in the overall design

process. This objective and trend applies to structuralanalysis and design. Key structural performance parametersinclude:

Higher performance structuresreduced weight withhigher degrees of safety and reliability

Lower fabrication costs Better economic performance in terms of lower

contribution to light ship and hence larger payloadfractions

Reduced structural maintenance costs over the life-cycle

Recognition of social responsibility in terms ofenvironmental protection, collision/damagetolerance, reduced risk of failure, etc.

Physics-Based Computer-Aided EngineeringNeeds to Occur Early in the Design Process

Early CAE-Centric

Design Processes

are Critical

Design Drivers

Figure 3. Physics-Based Computer-Aided Engineering

Early in the Design Process

5 IMPROVED INTEGRATION WITHOVERALL SHIP DESIGN PROCESS

Ship designs are now routinely developed initially in theform of surface models representing the hull and majordecks and bulkheads of the ship. This surface model canalso be viewed as a topological model that organizes thethree dimensional spaces of the ship, and defines the

purposes of the spaces and the relationships between thespaces. Advanced topology models become the masterorganizers of a ship design. The challenge for CAEmodels and analyses is to have a functional linkage or

relationship with the surface-based topology model(s).

Hullform

Sub-division& General

Arran gement

Parametric

StructuralModel

FiniteElementModels

Structural Design

Seakeeping &Hydro Loads

High

PerformanceComputers

StructuralEvaluation

LoadsModels

FESolvers

StructuralOptimizationITERATE

Weights

& Centers

CostAnalysi s

Ship

Signatures

Hydrostatics

Analysi s

Resistance &

Powering

Ship Topology Model

Improved Integration wi thOverall Ship Design Process

Figure 4. Structural Design Coupled with the Ship Design

Process

Figure 4 depicts:

Close coupling of ship surface topology withstructural analysis and design models, including

finite element models.


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Flowchart of Integrated Structural Analysis

STRUCTURAL OPTIMIZATION:

MAESTRO withDeMak (Multiple Methods)

Hydrodynamic

Load Prediction

STRUCTURAL INTEGRITY:Dynamic Load ApproachSpectral Fatigue Analysis

Underwater Shock

VibrationAutom ated Struc tural Panel Evaluati on

(IACS CSR, ALPS/ULSAP, MAESTRO Native)

Hydrodynamic/Structural Model Interface

S truct u ra l Changes? No

Yes

Hydro

Model

StructuralModel

STRUCTURAL LIFECYCLE:

CorrosionDamage Recoverability

Safe Operating Envelope

Structural DesignComplete

Figure 6. Structural Design Process

Open architecture structural design toolsets allowspecial purpose analyses such as Dynamic Load Approach

analysis, Spectral Fatigue Analysis, underwater shockresponse analysis for warships, free and forced vibrations, to

be introduced as requirements as defined by shipclassification societies and other safety authorities. Duringthe last few decades, methods useful for ultimate limit stateassessment of marine structures have been developed in theliterature. It is considered that such methods are nowmature enough to enter day-to-day design practice. (Paik,et al., 2007) An open architecture hosts multiple sets ofstructural integrity analysis and evaluation capabilities thatcan be invoked by the design team on a basis customized to

meet a specific set of ship requirements. The openarchitecture further enables the efficient introduction of newanalysis technologies as they transition from research toapplied practice.

Structural optimizationmethods provide capabilities tomove the structural design toward objective goals such asreduced weight and cost, while ensuring that all thenecessary structural integrity constraints and safety marginsare maintained. Hybrid solvers such asDeMak(Zanic et al.,2009) have been developed that organize multipleoptimization procedures that can be applied to specific

aspects of the structural design/optimization problem.DeMak includes five methods: 1) multilevel multi criteriasearch strategy; 2) fractional factorial design; 3) crosssection optimizer; 4) genetic algorithms; and, 5) multi-objective particle swarm optimization. These methods arecontrolled via a sequencer that gives the design team directcontrol over the application of the different optimizationmethods to different aspects of the structural design.

Structural lifecycle considerations including corrosion,fatigue, damage recoverability, and structural Safe

Operating Envelope determination, comprise another set ofcomplex ship structural performance elements which mustbe addressed as integral aspects with the design process.

These areas evolve from research and development, safetyauthority procedures, and owner/operator guidance andrequirements. An interesting source of these requirementshas been the development of ship classification rules fornaval vessels.

The rapidity and extent of the post-Cold Wardownsizing has caught many navies by surprise, forcing aglobal re-think of policies regarding acquisition, operationsand maintenance of warships on a scale not seen since theSecond World War. These navies are beginning to look toclassification societies as an important element in preservingthe technical standards of their current and future fleets,through the development of Rules, certification andclassification procedures for design, construction andthrough-life maintenance. (Ferreiro et al., 2001)

Feedback loop to the ship design model to return

changes in the structural design to the baseline ship designmodel(s) for re-analysis and evaluation. As Figure 6indicates the ship structural design process will evolvetoward a more unified set of modeling and analysiscapabilities and a more efficient and more effective set ofcomputer-based tools for performing the designdevelopment.

7 SUMMARY AND CONCLUSION

Next generation ship structural design tools and methods

must further unify structural design process sub-elementsinto a more efficient and higher fidelity process thatsupports the realization of engineering integrity withoptimized performance for the owner/operator. Advances indesign tool architecture, geometry and topology modeling,loads analysis, and structural evaluation must be betterunified in order to achieve progress toward these objectives.Strategies for implementing these improvements have beenin place for several decades now, and elements of the earlystrategies, for example the tenants of rationally-basedstructural design, have borne the test of time. On the otherhand, the degree of complexity of ship structural designcontinues to grow driven by the results of scientificdevelopment coupled with the ever-competitiveenvironment of ship owners and operators. As presentedherein, the vision of next generation ship structural designrequires more complete unification with both the basic shiptopology design and with the multiple aspects of shiploading and structural design. Furthermore, decisionsupport technologies and methods are here to stay and are

becoming more widely applied and accepted. Nextgeneration structural design will depend more on thesetechnologies to effectively explore the design space and

generate the best designs for ships of tomorrow.


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REFERENCES

Basu, R.I. et al., "Guidelines for Evaluation of ShipStructural Finite Element Analysis," SSC Report, SSC-387, Abstract, 1993.

Ferrerio, Larry, Ashe, Glen, Ingram, Thomas, Building theRules: The ABS Perspective on Developing

Classification Rules for Naval Vessels, RINASymposium, Warship, 2001.Hughes, Owen, Mistree, Farrokh, Zanic, Vedran: A

Practical Method for the Rational Design of ShipStructures, Journal of Ship Research, Vol. 24, No. 2,June 1980.

Hughes, Owen, "Ship Structural Design," John Wiley &Sons, New York, NY, 1983.

Mansour and Liu, "The Principles of Naval ArchitectureSeries: Strength of Ships and Ocean Structures,SNAME, Jersey City, New Jersey, Forward, 2008.

Paik J., and Thayamballi, "Ultimate Limit State Design ofSteel-Plated Structures," John Wiley & Sons, Ltd, WestSussex, England, 2008.

Paik, J. et al., Methods for Ultimate Limit StateAssessment of Marine Structures: A Benchmark Study,International Conference on Advancements in MarineStructures, Glasgow, UK, 2007.

Wheelwright and Clark, Leading Product Development,Harvard Business School, 1995.

Wood, R., Moore, S., The National Shipbuilding ResearchProgram Improved Methods for the Generation of Full-Ship Simulation/Analysis Models, NSRP AdvancedShipbuilding Enterprise, 2007.

Zanic, V., Adric, J., Prebeg, P., Kitarovic, S., Piric, K.,Multi-Objective Optimization of Ship StructuralTopology and Scantlings, Proceedings of theInternational Marine Design Conference, IMDC,Trondheim, 2009.

Zanic, V., Cudina, P., Multiattribute Decision MakingMethodology in the Concept Design of Tankers andBulk Carriers, Brodogradnja / Shipbuilding , Vol 60,

No.1, 2009.


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EU FP6 project IMPROVE-Final Conference

IMPROVE 2009, Dubrovnik, CROATIA, 17-19 Sept. 2009

Ship Design for Performance

Kai LevanderSeaKey Naval Architecture, Turku, Finland

ABSTRACT: Naval architects need a methodology for ship design that guides them through the design process. This

methodology should be open for new solutions and innovations. The capacity and performance of alternative solutions are

evaluated against a few major design criteria to optimize the ship for the intended mission. Key performance indicators are

use to select the most suitable design. Today energy efficiency and reduction of emissions have become very important

among these performance indicators.

1 INTRODUCTION

1.1

System based ship design

In their book Theory of Technical Systems Vladimir

Hubka and Ernest Eder describe the base for technical

systems and the benefits of system thinking in the design

work of complex products. Their methodology can be used

also in ship design, especially in the development of new

solutions. A ship must perform many different functions,

which all can be described as individual systems, butintegrated into the total ship mission. By defining each

system and the performance requirements for this system we

get a framework for the ship design. This is here called

System Based Ship Design. By adding simple algorithms

much of the ship design calculations can be automated

and performed by computer. This automation of the design

work makes it possible for the naval architect to spend more

time on improving the design and finding alternative

solutions. To compare different solutions and select the

most suitable design the naval architect must have clear

goals and evaluation criteria for the sea transport mission.

The essentials of system thinking Hubka and Eder

summarize as follows :

The theory of technical systems delivers the

relationships that are valid for all products

System thinking presents an opportunity to treat

problems as a whole

This is a necessary pre-condition for a successful

design and engineering effort

System thinking provides a framework for the

design task and formalize many logical operations

Use of computers during the design process depends

on formulating algorithms for those design

operations, where logical treatment is possible

System thinking also supports those human

operations, that are not strictly logical, like intuition

and creativity

1.2 Cargo transportation business

Transportation by sea is often the best alternative for

large volumes and long distances. But the owner of thecargo should also evaluate other alternatives, like transport

by road or rail or perhaps by air if fast delivery is important.

The cargo owner has in fact the possibility to relocate the

factory closer to the market to reduce the logistic cost. If

transportation by sea is chosen the cargo must be transferred

to the port, loaded into the ship, unloaded in the port ofdestination and distributed to the customer. The cargo must


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This model easily locks the naval architect to his first

assumption. He will patch and repair this single design

concept rather than generate alternative. An approach that

better supports innovation and creativity should be used.

System based design starts from the mission specified for

the ship. There are two types of input data, demands that

must be followed and preferences that describe goals.

Dividing requirements into musts and wants makes it

possible to reduce the design work needed to find a

technically feasible and economically preferable solution

(Figure 4).

Figure 4. Ship design phases

Initial sizing of the ship

The initial sizing is based on the space needed for the

payload and for the supporting systems needed onboard the

ship. In a tanker the volume of the cargo tanks and the

protecting double hull defines a major part of the space

needed in that ship (Figure 5). The double hull is used for

ballast water on the return voyage, when there is no oil in

the cargo tanks.

In a cruise ship the sizing is based on the passenger

facilities needed onboard. But also crew and service spaces

demand much space. In addition technical spaces for

machinery, tanks for fuel, fresh water, etc. requires much

space (Figure 6). But this sizing principle is basically the

same for all ship types and gives the total volume of the

ship in m3.

Figure 5. Initial sizing of double hull tanker


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Another measurement of ship size is displacement,which indicates the weight of the ship itself and the cargoand stores carried onboard. The displacement governs theselection of main dimensions and hull shape (Figure 8)

This has great impact on the power needed forpropulsion of the ship at the desired speed. The main taskfor naval architects is to establish the Gross Volume anddisplacement needed in the ship to fulfil the intendedtransport task.

Figure 8. Acrhimedes' Law

1.4 Hip design process

The starting point is the mission and the functions of theship (Figure 9). All systems needed to perform the definedtasks are first listed. The areas and volumes demanded inthe ship to accommodate all systems are then calculated.The ship systems are divided into two main categories,

payload function and ship function. In a cargo vessel the

payload functions consist of cargo spaces, cargo handlingequipment and spaces needed for cargo treatment onboard.

The ship functions are related to carrying the payloadsafely from port to port (Figure 10). This design methoddoes not need pre-selected main dimensions, hull lines orstandard layouts. System based design is like a checklistthat reminds the designer of all the factors that affect thedesign and record his choices. The result is a completesystem description for the new ship, which will act as the

base for further design work (Figure 11).

Figure 9. The ship design process

Figure 10. Payload and ship functions


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Figure 11. System based ship design


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2 SHIP DESIGN CRITERIA

2.1 Design criteria for cargo ships

For cargo ships there are 3 main factor affecting the technical feasibility and the profitability of the design

Figure 12. Design Criteria No.1 - DWT/Displacement


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Figure 14. Key performance indicators for cargo vessels

2.3 Energy efficiency

IMO is interested in the environmental friendliness ofshipping and wants to establish a energy efficiency index tohelp designers, builders and operators to evaluate the carbonemissions of ships and to establish goals for the reductionefforts. The equation above could be incorporated as partof the IMO regulations on the EED.

The Power Factor is a good indicator for the energyefficiency of different ship types and sizes. In Figure 15 youcan see the benefits of large, slow tankers and bulk carriers.Even very large container vessels cannot compete with themin fuel efficiency.

This Energy Efficiency Index is very similar to thePower Factor that compares the power demanded to theship deadweight and service speed. This Power Factor canalso be used as the design criteria for CO2 emissions. CO2emissions are directly related to fuel consumption for shipsoperated on the same fuel.

Also RoRo vessels are far above tankers and bulkcarriers in fuel consumption per transported cargo andnautical mile. Today all these ship types have diesel-mechanical machinery and use MDO or HFO as fuel.

nmton

kWh

SpeedDWT

powerPropulsionPF

Power Factor


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METHODS and TOOLS


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New and Updated Modules to Performed Stress and Strength Analysis


Figure 1 Eight - node isoparametric finite element for

analysis of the corrugated bulkheads and fine mesh

validation model in NASTRAN

For the evaluation of a quality of coarse macroelement

mesh using anisotropic finite elements, two 2D OCTOPUSmodels were generated: one with the simple plate elementswith stiffeners (model A1) and the other with the anisotropicfinite elements (model A2). The results of OCTOPUSmodels were compared with the NASTRAN model, Fig. 2.

Figure 2. Comparison of displacements of OCTOPUS and

NASTRAN model

Comparison of OCTOPUS model A2 with NASTRANfine mesh model shows very good agreement of

displacements andy

normal stress. For model A2 the

displacements vary up to 5% andy normal stresses vary

up to 15%. The results of OCTOPUS model with simpleplate elements with stiffeners (model A1) are not acceptablecompared with the results of the model A2.

2.2 Equivalent modeling of double bottom elements

Through this sub-task the development and validation of

the double-hull element was preformed taking into accountthe additional stiffness brought by the double-hull webframes as well as the link they constitute between these webframes and the double-hull plating (inner hull and outerhull), (Rigo, 2005). The integration of the double-hullelement inside the optimization process, involving the(analytical) computation of sensitivities with respect todesign variables was achieved.

Figure 3. Modeling of the structure in LBR-5

This new functionality has been validated by comparingresults obtained with those coming from Finite ElementAnalysis and Solid Mechanics Theory. Convergence of theresults obtained with LBR-5 in terms of the number ofFourier terms as well as the order of magnitude of theseresults are totally acceptable.

2.3 Equivalent modeling of cofferdam

Through this sub-task the development and validation ofmodeling of cofferdams using LBR-5 software is presented.The goal of this task is to allow the optimization tool to takeinto account the cofferdam structure during the structuralanalysis and the optimization process.


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New and Updated Modules to Performed Stress and Strength Analysis


Figure 2. Drawing of the cofferdam and model in Rhino

The stresses obtained in the symmetry axis with LBR5are in average 15-20% higher than the FEM solution for thetwo load cases. The differences are due to several reasons,including the LBR5 geometry and scantlings

approximations and the differences between the twoconsidered methods for the analysis. The differences at theextremities are influenced by the boundary conditions andthe rectangular shape used by the LBR5 model, thereforethey will not be considered in the calibration.The proposedmethodology can be considered as a general way tooptimize several structures (or sub-structures) at the sametime, but the development done in this chapter is onlyfocusing on the LNG cofferdam structure.

3 VALIDATION OF STRESS / STRENGTHMODULES FOR CONCEPT DESIGN

3.1 Modules for direct calculation of the

longitudinal and transverse strength

Modules for direct calculation of the longitudinal andtransverse strength have been examined and improved inOCTOPUS software. The comparison between 2DOCTOPUS and generic 3D MAESTRO models of RoPaxare carried out. Accuracy of longitudinal stress distributionover ships height in OCTOPUS model found to be

satisfactory compared to generic 3D MAESTRO model forthe purpose of concept designs. Accuracy of stressdistribution over the transverse beams breadth in OCTOPUSmodel was found to be satisfactory compared to the 3D FEmodel. Similar validation has been performed with LBR-5modules and compared to VERISTAR results. It also gavesatisfactory results for the concept design phase.

3.2 Development and validation of simplified

generic 3D FEM models for co

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